Biomechanical Changes of the Spinal Cord Caused by Chiari I Malformation

Summary

Biomechanical and hydrodynamic analysis of the spinal cord was performed to understand the pathogenesis of syringomyelia associated with Chiari I malformation. A finite element analysis of intraspinal stress distribution was done by a newly developed two-dimensional elastic craniocervical model of Chiari I malformation. The finite element model was refined to simulate the effect of the generation of an intraspinal cavity on stress distribution. Three different models—normal, Chiari I malformation, and Chiari I malformation with syrinx—were constructed with triangular elastic elements. Different material properties such as brain, spinal cord, disk, bone, and cerebrospinal fluid (CSF) were added to each element. On neck extension and flexion, the calculated intraspinal stress was concentrated in the upper cervical spinal cord where the cerebellar tonsil had herniated. The presence of the intraspinal cavity generated stress around the cavity itself. Intraspinal stress concentration associated with the presence of Chiari I malformation may play a role in syrinx initiation, after which the formation of a small syrinx promotes further stress concentration around it and results in the progression of the syrinx.